Realization of a 4 kHz, large energy single-frequency ns optical parametric oscillator by suppressing optical parametric generation.

Large energy single-frequency nanosecond (ns) near-infrared light source is an essential device in the field of the remote chemical analysis based on the laser-induced breakdown spectroscopy (LIBS). In this paper, a large energy single-frequency ns 824 nm light source with high repetition rate is presented, which is generated from a seed-injection locked optical parametric oscillator (OPO). By optimizing the spot radius of the pump laser and the mode-matching between the pump laser and signal light, the optical parametric generation (OPG) process is effectively eliminated. On this basis, with the assistance of the seed-injection locking, a single-frequency 4 kHz ns 824 nm light source with an output pulse energy and a spectral width of 3.39 mJ and 32.42 MHz is obtained. For the best of our knowledge, it is the largest energy for the single-frequency ns near-infrared light source with the repetition rate of kHz level.